This invention relates to a wireless remote sound monitor, such as a nursery monitor.
Wireless monitors, such as those used to monitor the sounds of a baby, typically include two components, namely, a monitoring unit and a receiving unit. The monitoring unit is placed near the child and includes a microphone for picking up the sounds made by the child and a transmitter for sending the audio sounds over a radio signal to the receiving unit, preferably a portable unit carried by the parent or supervising adult, which includes a loudspeaker. Either or both the monitoring unit and the receiving unit may be battery powered or they may be provided with a source of power from an external power adapter that is connected to a commercial power outlet. In some monitoring devices, a voice or sound actuated circuit is used to turn on the monitoring unit's transmitter only when the sound level is above some predetermined level. This is done to conserve power and increase battery life. When using sound actuation of the transmitter, however, even careful listening cannot reveal whether the system is operational. If the baby being monitored is silent, then the transmitter will be off, but from the parent's point of view, does that mean the baby is really silent or has there been a failure of the equipment?
There is clearly a need to provide a wireless monitoring system where the user can know with certainty that the equipment is operating properly, even when there is no sound being generated at the monitored location.